/*****************************************************************************

Copyright (c) 2007, 2009, Innobase Oy. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 
51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

*****************************************************************************/

/**************************************************//**
@file include/ha0storage.h
Hash storage.
Provides a data structure that stores chunks of data in
its own storage, avoiding duplicates.

Created September 22, 2007 Vasil Dimov
*******************************************************/

#ifndef ha0storage_h
#define ha0storage_h

#include "univ.i"

/** This value is used by default by ha_storage_create(). More memory
is allocated later when/if it is needed. */
#define HA_STORAGE_DEFAULT_HEAP_BYTES	1024

/** This value is used by default by ha_storage_create(). It is a
constant per ha_storage's lifetime. */
#define HA_STORAGE_DEFAULT_HASH_CELLS	4096

/** Hash storage */
typedef struct ha_storage_struct	ha_storage_t;

/*******************************************************************//**
Creates a hash storage. If any of the parameters is 0, then a default
value is used.
@return	own: hash storage */
UNIV_INLINE
ha_storage_t*
ha_storage_create(
/*==============*/
	ulint	initial_heap_bytes,	/*!< in: initial heap's size */
	ulint	initial_hash_cells);	/*!< in: initial number of cells
					in the hash table */

/*******************************************************************//**
Copies data into the storage and returns a pointer to the copy. If the
same data chunk is already present, then pointer to it is returned.
Data chunks are considered to be equal if len1 == len2 and
memcmp(data1, data2, len1) == 0. If "data" is not present (and thus
data_len bytes need to be allocated) and the size of storage is going to
become more than "memlim" then "data" is not added and NULL is returned.
To disable this behavior "memlim" can be set to 0, which stands for
"no limit".
@return	pointer to the copy */
UNIV_INTERN
const void*
ha_storage_put_memlim(
/*==================*/
	ha_storage_t*	storage,	/*!< in/out: hash storage */
	const void*	data,		/*!< in: data to store */
	ulint		data_len,	/*!< in: data length */
	ulint		memlim);	/*!< in: memory limit to obey */

/*******************************************************************//**
Same as ha_storage_put_memlim() but without memory limit.
@param storage	in/out: hash storage
@param data	in: data to store
@param data_len	in: data length
@return		pointer to the copy of the string */
#define ha_storage_put(storage, data, data_len)	\
	ha_storage_put_memlim((storage), (data), (data_len), 0)

/*******************************************************************//**
Copies string into the storage and returns a pointer to the copy. If the
same string is already present, then pointer to it is returned.
Strings are considered to be equal if strcmp(str1, str2) == 0.
@param storage	in/out: hash storage
@param str	in: string to put
@return		pointer to the copy of the string */
#define ha_storage_put_str(storage, str)	\
	((const char*) ha_storage_put((storage), (str), strlen(str) + 1))

/*******************************************************************//**
Copies string into the storage and returns a pointer to the copy obeying
a memory limit.
If the same string is already present, then pointer to it is returned.
Strings are considered to be equal if strcmp(str1, str2) == 0.
@param storage	in/out: hash storage
@param str	in: string to put
@param memlim	in: memory limit to obey
@return		pointer to the copy of the string */
#define ha_storage_put_str_memlim(storage, str, memlim)	\
	((const char*) ha_storage_put_memlim((storage), (str),	\
					     strlen(str) + 1, (memlim)))

/*******************************************************************//**
Empties a hash storage, freeing memory occupied by data chunks.
This invalidates any pointers previously returned by ha_storage_put().
The hash storage is not invalidated itself and can be used again. */
UNIV_INLINE
void
ha_storage_empty(
/*=============*/
	ha_storage_t**	storage);	/*!< in/out: hash storage */

/*******************************************************************//**
Frees a hash storage and everything it contains, it cannot be used after
this call.
This invalidates any pointers previously returned by ha_storage_put(). */
UNIV_INLINE
void
ha_storage_free(
/*============*/
	ha_storage_t*	storage);	/*!< in, own: hash storage */

/*******************************************************************//**
Gets the size of the memory used by a storage.
@return	bytes used */
UNIV_INLINE
ulint
ha_storage_get_size(
/*================*/
	const ha_storage_t*	storage);	/*!< in: hash storage */

#ifndef UNIV_NONINL
#include "ha0storage.ic"
#endif

#endif /* ha0storage_h */
